Compression, storage, &amp;c., of ethylene



A. A. BACKHAUS. COMPRESSION, STORAGE, &c., 0F ETHYLENE.

APPLICATION FILED JUNE 6,1919. 1,339,431. Patented May 11, 1920.

2 SHEETS-SHEET I.

GWINVENTOR ATTORNEYS HAUS, residing at UNITED STATES PATENT OFFICE.

ARTHUR A. BACKH'AUS, or-mmmonn,

m ma, ASSIGNOR To U. s. INDUSTRIAL ALCOHOL COMPANY, OF-NEW YORK, N. Y.,A CORPORATION OF WEST VIRGINIA.

,comrnnssron, s'ronAGE, m, or ETHYLENE.

Specification of Letters Patent.

Patented May 11, 1920.

Application lnea June 6,1919. Serial na-aoaaoe.

To all whom it may concern: I

Be it known.that'I,.AnrHUR A. BACK- land, have invented certain new anduseful Improvements lilthe Compression, Storage,

&c., of Ethylene; and Ido hereby declare the following to be a full,clear, and exact description-of the invention, such as w1ll enableothers skilled-in the art to which it' .appertains to make and use thesame.

The presentinvention relates to improvements in the compression,storage, etc., of ethylene, whereby the ethylene, in large amount, canbe' advantageously shipped and made available for use in a highlycompressed state, blow-pipe: fuel, or for other purposes. 7'

Various combustible gases have heretofore been provided in containersunder pressure for use in combustion processes, as in the production ofa blowpipe flame for use in heating, welding, cutting, etc., or forother purposes. The-combustible gases which have been mostcommonlysupplied in this way have been hydrogen, Blau gas and acetylene.Hydrogen; can be readily compressed to a high degree, but it is de-lficient in heating power and is of relatively little importance as afuelfor commercial purposes.

Blaii gas issupplied' in special containers or cylinders in a liquefiedstate, 7 but its evaporation and use require special precautions, andare attended with certain well recognized disadvantages; The gas mostcommonly employed as a combustible gas,'an d supplied under pressure incon-.

tainers, is acetylene, and this gas, in spite of d the its objectionablecharacteristics, an compression, storage and use, prevails, at present,in the commercial field.

The danger incident to the manufacture, compression, storage and use ofacetylene is well appreciated in the art. In order to make acetyleneavailable at all for trans portation and use in a compressed state, va-

rious expedients ,must be resortedto, but

these have been only partially successful, and have served merely toreduce-and not to eliminate the inherent and constant menace and perilof spontaneous explosion,

Thus, in practice, the cylinders in which acetylene is compressed mustbe first completely filled with a porous material, and this materialmust be charged or soaked with ac'etone, orits equivalent, which serves.as

Baltimore, State of Marystored,

for example,- as' a upon its manufacture,

a solvent for the acetylene. The acetylene is then introduced anddissolved inthe sol-- vent. It is important for the cylinder to.

the solvent. The permissible pressure of the charged cylinder is limitedto about 250 pounds per square inch at a temperature of about 7 0;F.Acetylene is well known to ,be explosive when in a compressed state anda rise intemperature and pressure of the cylinder and its contents dueto exposure of the cylinder toa high temperature, will often bring aboutan explosion. The formation of explosive acetylids is'also a source ofdanger.

Further disadvantages incident to the compression, storage 'and supplyof acety lene are the inevitable loss by evaporation of a part of theace one solvent, which must be replacedwhent e cylinder is recharged;the presence of deleterious constituents,

such,- as phosphids, which may be present when acetylene "is obtainedfrom carbid;

and the' instability of the acetylene which results in its decompositionwhen it is heatedto a high temperature during use. So also, particularlyin extremely'cold weather, the lowering of temperature due to theevaporation of theacet lene and acetone may result in a partial reezingof the contents of thecylinder, so that the user is unable to obtainfrom the cylinder the same uantity of acetylene, as is obtainable thererom-in summer. Moreover, in some instances the user, 'unaware of thedanger of the expodient, is tempted to Warm up the cylinder for therelease of the residual acetylene, and

.is exposed to peril incident tothat procedure.

Furthermore, the protective filling and solvent, required in anacetylene cylinder, not only involve an additional expense in initialexpense and in subsequent maintenance and replacement, but theymaterially increase the weight of the cylinder, so that the handling andtransportation of both the charged and empty cylinders involves addedeffort and expense.

According to the present invention, the difficulties and objectionsreferred to are avoided, and there is provided a compressed fuel gas,namely, compressed ethylene,

which can be compressed, stored, shipped and used without danger, andwhich, in addition, presents certain features of advantage overacetylene and the other available compressed fuel gases;

Chemically considered, ethylene is closely related to acetylene. Both.are unsaturated hydrocarbon gases containing two carbon atoms, and theonly two such gases. They differ, chemically, only in their degree ofunsaturation, z. 6., in the numberof hydrogen atoms which they contain,and, by hydrogenation, bothgases can be converted into the samesaturated hydrocarbon, namely, ethane. It might, therefore, be expectedthat ethylene, because of its close chemical similarity to acetylene,would likewise require special precautions in its compression, storageand use, and be subject to like limitations.

I have found, however, that ethylene can A be directly compressed to ahigh pressure,

far in excess of that to which acetylene can be safely compressed, andthat ethylene can be stored in cylinders or containers without theme ofan absorbent filling and 'solvent, and ithout the danger anddisadvantages incident to the compression and storage of acetylene. Theentire space of the cylinder can, accordingly, be filled with thecompressed ethylene. ,Moreover, since the ethylene is present in agaseous, rather than a dissolved or liquid state, the entire content ofthe cylindefan be made available, .even in the cold est; weather,without objectionable lowering of temperature due 'to evaporation. I

I have made the further surprising dis- .covery'that the amount ofethylene which can be safely charged into a cylinder of standardconstruction is more than twice as great as the amount of hydrogen(likewise acombustible gas and a component of ethylene), or of oxygen(the common combustion-sup orting gas), which can be safelycharg d'intoa cylinder ofthe same size and construction.

This important difference between ethyl ene and gases such as hydrogenand oxygen is further emphasized by the profound infiuence which thetemperature of compression andecharging has upon the pressure requiredfor the chargingpperation. Thus, if the limiting conditionof thecylinder is a pressure of about 2200 lbs. at a maximum temperature ofabout 50C. or 122 F., a cylinder, thecubical content of which is 1 cu.ft.,- will .contain about 288 cu. ft. of free ethylene, whereas thissame amount of ethylene need only be compressed to a pressure of about1320 lbs. (:per sq. inch abs.) if the temperature of the ethylene islowered to about 203 C. I

In; the charging of cylinders with oxygen it is customary to charge theoxygen at or- ,in s, in which,

of about 2000 lbs. and at a temperature of about 203 and an increase intemperature up to about 50 0., will cause but a relatively smallincrease in pressure to about 2200 lbs, The amount of free oxygen socharged will be about 147 cu. ft. 'In the case of ethylene, however, ifthe cylinder were charged at the same temperature andpressure, theamount of ethylene will be about 360 cu. ft., and, if the temperatureshould increaseto 50 (3., the pressure would increase to about 3900.lbs.-far beyond the pressure for which the ordinary cylinder isconstructed.

The compression of ethylene is accom panied bytheevolution ofconsiderable heat,

and by a corresponding rise in temperature It is, therefore, important,in order to avoid too high temperatures and pressures, to. subject theethylene to cooling during its compression, and thereby absorb andneutralize the heat of compression. This cooling is also of advantage inenabling a lower pressure to be used at the lower temperature, owing tothe greater ease of. compression of ethylene at the lower temperatures,as above indicated.

The invention will be further described in connection with the.accompanying drawlgure 1 shows, in tional and diagrammatic manner, anarrangement of apparatus for compressing and cooling'the ethylene andcharging it into the containers; and Fig. 2 shows a chart by means ofwhich the proper charging pressure can be ascertained for any usualcharging temperature.

In the apparatus of Fig. 1, the ethylene,"

from the generator or storage tank, is introduced through the .pipe 1 tothe first cylinder 2 of a three stage compressor. The three cylinders ofthe three successive stages are indicated at 2, 6 and 10, respectively,and are each provided with a cooling jacket for absorbing. part of theheat of compression and thereby keeping down the tern perature of thecompressed ethylene. From the three compression. cylinders the'compressed ethylene passes through the three respective coolers orexchangers, where it is brought into indirect contact with water orother cooling agent, and its temperature is still further lowered. Theconnecting p'i 'es are indicated at 3, 5 7, 9 and 11.

rom the. last cooler 12, the com ressed and cooled ethylene passesthrough t e pipe 13 to the charging manifold 14, having branches withvalves 16 and fiexlble pipe connections or pig-tails 17 through whichthe cylinders 15 may be charged.

Each cylinder is provided with the usual a somewhat convencommonlyprovided with 'spect, accordingly,

eth lene to be readily ascertained.

he'pressure to which the ethylene will require compression or to whichit can be safely compressed, will vary with the temperature, as abovestated. -The extent of this variation will be apparent'from Fig. 2,which is based upon observed figures. Assuming a maximum pressure ofabout 2200 lbs., at a maximum temperature of 50 (1. as the limitingconditions, the charging pressure for any lower temperature can bereadily ascertained, inasmuch as the volume of the cylinder, and thenumber of cubic feet to be charged (about 288 cu. ft. of free ethyleneat 20 C. and atmospheric pressure) will remain the same. At 163 C. thispressure will be only about 1050 lbs.; at 203 C., about 1350 lbs.; at30.1 C., about 1630 lbs.; and at 10 0., about 1880 lbs. If the cylinderhas a higher safe charging pressure, e. 9., about 3000 lbs., at amaximum temperature of 50 0., it will require a charging pressure ofonly about 1500 lbs. at 103 0., or about 1800 lbs. at 203 C. Thecorrespondingly greaterease of compression, and the much less powerrequired for the compression, at lower temperatures, will thus beapparent, as well as the profound effect of increase in temperature on.the pressure of the ethylene so charged. A very important economy in thepower required for compression and charging of the ethylene will resultfrom even a few degrees lowering of the temperature. Accordingly, byproviding for the aftercooling of the compressed ethylene, and therebyreducing its temperature, it becomes possible not only to use less powerfor the compression,- but also to use a compressor of less expensiveconstruction, thereby economizing both in the initial expense of thecompressor and in the cost of its operation. With hydrogen and oxygen,there is no particular advantage to be gained by after-cooling of thecompressed gases, inasmuch as the power. required is but slightlyreduced bysuch after-cooling. In this reas well as in other respectselsewhere pointed out, the process of compression and charging ofethylene differs radically from that of hydrogen and oxygen. q

' hereas with hydrogen or oxygen the variations in pressure due to thevariation in temperature commonly met with, are so small as to be withinthe margin of safety of the common metalcylinders, (which are safetydevices that will be ruptured at excessive pressures, e. 9., about 400lbs. in excess of the charging pressure for which the cylinders aretested) the variations in pressure with ethylene due is maintaine tolike Variations in temperature are far inexcess of the safety limit.

It is accordingly necessary, with ethylene, to take precautions notrequired in the handling of these other gases. With the observation ofthese precautions, however,

and by proper cooling and regulation of I the charging temperature andpressure, it is nevertheless possible to charge the compressed ethylene,so that it can be safely stored, handled, transported andused, and

' so that it will, nevertheless, contain a far greater number of cubicfeet of ethylene than a like cylinder would contain of other combustible gases, such as hydrogen or acetylene. It is thus readilypossible to charge more than one and a half or two times as muchethylene as hydrogen into a standard cylinder (about 1.54 cu. ft.capacity) at the same or a lower pressure, and such cylinders with theirfar larger amount of ethyl-' ene, can nevertheless be stored, handled,transported and used with substantially the same ease and safety as theordinary hydrogen cylinders. That is, whereas acylinder having a cubicalcapacity of about .777 cubic foot is commonly called a 100 cubic foothydrogen or oxygen cylinder, and a cylinder having a cubical capacityof'about=1.51 cubic feet is commonly called a 200 cubic foot hydrogen oroxygen cylinder; the amount of ethylene which can be safely charged intothese same cylinders will be more than one and one-half times as much,and may amount to twice as much or even more. Expressed in terms, ofcubic feet of ethylene per cubic foot of cylinder capacity, it is thuseasily possible to charge more than 200 cubic feet of ethylene, and evenmore than 250 cubic feet of ethylene, per cubic foot of cylindercapacity, without danger, whereas, with hydrogen or oxygen the cylindersabove referred to contain only about 130 cubic feet of hydrogen oroxygen per cubic foot of cylinder capacity. I

When the c linder of compressed ethylene at ordinary temperature, or itcooler temperatures,the pressure exerted y and the margin of safety ofthe cylinder correspondingly increased. Q

When in use, ethylene which a cylinder of compressed ethylene willcontain, as compared .with cylinders of hydrogen or acetylene of like sze, will enable the ethylene to be used for a change of cylinders.

the far larger amount of ders required to be purchased and kept on Ihand can thus be radically reduced, with resulting saving intransportation charges, "and in initial expense of the cylinders.

\ Ethylene can be readily produced in a state of comparative I urlty,7,. 6., containmg 95% or more ethy ene, and without the purity. Thus,for example, it may be obavailable quantities.

- free from absorbent tained by the liquefaction and fractionalseparation of oil gas or crackedoils or other gaseous mixtures 1n whichit ls flpresent in I recommend, however, as the preferred source of theethylene, obtaining it bythe catalytic dehydration of ethyl alcohol,employing, for example, alumina, clay or other like catalytic body at asuitable temperature. The ethylene may be produced ina continuous mannerand supplied directly. to the compressor, or it may convenientlybestored in a suitable holder and supplied to the compressor as re ui'red.

claim l 1. A' commercially transportable metal cylinder containingcompressed ethylene which can,be safely stored, handled, shipped andused, said cylinder having its interior filler and solvent andcontaining the ethylene compressed to a high pressure, the amount ofethylene being more than one and one-half times of hydrogen in acylinder of the same size under the same pressure; substantially asdescribed.

2. A commercially transportable metal cylinder containing compressedethylene which can be'safely stored, handled, shipped and used, saidcylinder having its interior free from absorbent filler and solvent andcontaining the ethylene compressed to a high pressure; the amount ofethylene being more than 200"cubic feet of ethylene per cubic foot ofcylinder capacity; substantially as .described. I v3. A commerciallytransportable metal" cylinder containing compressed ethylene which canbe safely stored, handled, shipped and used, said cylinder having itsinterior free: from absorbent filler and solvent and containing theethylene compressed to high pressure, the amount of ethylene beingmorethan 250 cubic feet of ethylene percubic foot of cylinder capacity;substantially as described.

4. The method of compressing ethylene in cylinders, for storage,shipment and use,

which comprises. compressing the ethylene,

cooling the ethylene during compression and I thereby neutralizing theheat of compres sion and materially lowering the pressure the amountrequired, and charging the cooled com pressed ethylene under a regulatedpressure and ina gaseous state into cylinders havin their interiors freefrom packing and so vent, the charging pressure being so regulated thatthe amount of ethylene charged into the cylinders will be more than oneand one-half times the amount of hydrogen in cylinders of the same sizeunder the same pressure; substantially as describe v 5. The method ofcompressing ethylene in cylinders for storage, shipment and use, whichcomprises subjecting the ethylene to progressively increasedcompression, cooling the ethylene during such progressive compressionand thereby neutralizing the heat of compression, and materiallylowering the pressure required, and cooled compressed ethylene at atemperature of about 20 C. to 40 C., and under a regulated pressure intocylinders havin their interiors free from packing and so vent, wherebythe ethylene is contained in the cylinders in a compressed gaseousstate, the charging pressure being so regulated that the amount ofethylene charged into the cylinders will be more than 250 cubic feetture and pressure being so regulated that the amount of ethylene chargedinto the cylin ders will be more than one and one-half times the amountof hydrogen in cylinders of the same size under the same pressure;substantially as described.

7,. The method of compressing ethylene in cylinders for storage,shipment and use,

charging the which comprises compressing the ethylene,

cooling the ethylene both during and after compression and therebyneutralizing the compression and materially lowerheat of ing thepressure required, and charging the cooled compressed ethylene intocylinders having their interiors free from packing and solvent, thecharging temperature and pressure being so regulated that the amount ofethylene charged into the cylinders will be more than one and one-halftimes the amount of hydrogen in cylinders ofthe same size under the samepressure; substantially as described.

In testimon whereof I aifix m si ature.

4 A THUR A. BAClhffA US.

